Nanoparticles of Zinc Oxide Reduces Acute Somatic Pain in Adult Female Wistar Rats

Background: With appearance of nano particles as an important component in modern medicine, and considering to new properties of these components, study of their effects on human health is essential. Since zinc components influences mechanisms of nociception, the aim of this study was to evaluate the effect of nano zinc oxide as a new source of zinc and important components in pharmaceutical and hygienic cosmetic production on nociception in adult female rats. Materials and Methods: Female rats were divided into groups: control (receiving saline 0.9%) and receiving nano ZnO (0.5, 1, and 5 mg/kg). Hot plate and tail flick tests as models of somatic acute pain were used for evaluation of the pain. The mean of latency time in paw licking and tail withdrawal respectively recorded as nociception indexes in each test for every animal. The animal numbers in each group was seven. Results: In tail flick test, nano ZnO (0.5, 1 mg/kg) and in the hot plate test in dose of 0.5 mg/kg, induces significant analgesia (p < 0.05) and with increasing of dose reduced its analgesic effect. Conclusion: It seems nano ZnO inhibit the nociception mechanisms and these analgesic properties are more efficient in the low doses. Probably by increasing dose of nano particles aggregation phenomenon prevent of anti-nociception effects of nano ZnO.